In certain high security situations, high security locks of the type which utilize an automatic dead lock tripper are used. The dead lock tripper automatically relock the lock when the door or other component on which the lock is mounted closes into its jamb or the like. This invention is directed to a safety mechanism for these types of locks wherein an override mechanism element is utilized to prevent the automatic locking of the lock during normal use. The override mechanism can be controlled via a secondary key.
Certain high security locks are known which include automatic dead lock trippers which relock the lock when a door or other closure means to which the lock is attached is placed from an open to a closed position. Normally, these high security locks are of the dial or combination type which do not require a key. They are utilized in certain security situations where it is desirable to prevent ingress into the high security area.
The base or body of these locks is placed on the inside of the door leading to the security area. The combination dial or the like is placed on the outside of the door with a shaft passing through the door between the dial and the base. Normally, a mechanism is included on the base which would therefore be located on the inside of the door, which allows egress from the security area. When these locks are used as manufactured, the door can only be opened from the outside by dialing the appropriate combination. As soon as the door is closed again, the automatic deadlock tripper relocks the door, such that if ingress to the security area from outside of the door is again required, once again the combination must be properly dialed. However, on the inside of the security area, since the dial is not available for unlocking the lock, a knob or the like is provided to allow persons in the high security area to exit from this area. This is necessary for safety reasons and the like wherein it is impractical to "lock someone in" from the outside.
The mechanism used on the base of the lock to allow a person to leave the security area requires certain physical dexterity to operate. In an emergency situation, those having physical handicaps of their hands, such as arthritis or missing digits or the like, are unable to manipulate these controls to open up the lock so as to be able to exit from the security area. This could impose a life threatening situation in case of fire or the like in the high security area. Further, those confined to wheelchairs or the like may not be of sufficient elevation to operate these mechanisms to open the lock and thus exit the high security area.
In other situations, it is sometimes desirable to unlock these high security locks and leave them unlocked for a period of time but to be able to easily reset the locks to prevent access to the high security area when required. Even the emergency release knobs presently forming a part of these locks do not allow normal ingress through the outside of the door during such working situations described above. Only those having knowledge of the combination of the lock are able to enter into the high security area. Since it is not desirable to carte blanche issue the combination to all those who might require access to the high security area during normal working hours, these people must continually seek assistance in order to enter the high security area. This is both time consuming with regard to interrupting other personnel as well as time consuming to the person awaiting access to the high security area.